Rotary lawnmowers employ a horizontally rotating blade which whirls at sufficiently high speeds to cut grass as the vehicle housing the rotating blade is moved over the lawn. The typical blade is a metal bar with a sharpened edge at each end of the bar and with means for mounting the bar on the rotating shaft of a motor so that the bar rotates in a horizontal plane with a cutting edge at each end of the bar. Many instances have occurred where persons were injured while operating a rotary lawnmower or while being an innocent bystander when the rotating bar hit a rock or other hard object causing chips from either the bar or from the hard object to fly out from underneath the mower hitting and injuring the person near by. In a more recent development the metal bar has been replaced by a tough synethic filament, e.g. nylon, which extends outwardly from a central rotor and the whirling filament acts like the small end of a whip cutting the grass in an efficient and proper manner. The advantage of employing the filament cutter in place of a metal blade is that when the filament cutter hits a hard object such as a rock it will not break the rock and cause any flying chips to be flung outwardly with the possibility of injuring any person neary.
It is an object of the present invention to provide a well designed rotor assembly employing filament cutting members. It is another object of this invention to provide a rotor assembly employing filament cutting members and having shear pins as a safety provision. Still other objects will be apparent from the more detailed description of this invention which follows.